BCMA (B-cell maturation antigen, TNFRSF17, CD269) is a transmembrane protein belonging to the TNF receptor super family. BCMA is originally reported as an integral membrane protein in the Golgi apparatus of human mature B lymphocytes, i.e., as an intracellular protein (Gras et al., (1995) International Immunol 7(7):1093-1105) showing that BCMA seems to have an important role during B-cell development and homeostasis. The finding of Gras et al. might be associated with the fact that the BCMA protein that was described in Gras et al. is, because of a chromosomal translocation, a fusion protein between BCMA and IL-2. Meanwhile BCMA is, however, established to be a B-cell marker that is essential for B-cell development and homeostasis (Schliemann et al., (2001) Science 293 (5537):2111-2114) due to its presumably essential interaction with its ligands BAFF (B cell activating factor), also designated as TALL-1 or TNFSF13B, and APRIL (A proliferation-inducing ligand).
BCMA expression is restricted to the B-cell lineage and mainly present on plasma cells and plasmablasts and to some extent on memory B-cells, but virtually absent on peripheral and naive B-cells. BCMA is also expressed on multiple myeloma (MM) cells. Together with its family members transmembrane activator and cyclophylin ligand interactor (TACI) and B cell activation factor of TNF family receptor (BAFF-R), BCMA regulates different aspects of humoral immunity, B-cell development and homeostasis. Expression of BCMA appears rather late in B-cell differentiation and contributes to the long term survival of plasmablasts and plasma cells in the bone marrow. Targeted deletion of the BCMA gene in mice does not affect the generation of mature B-cells, the quality and magnitude of humoral immune responses, formation of germinal center and the generation of short-lived plasma cells. However, such mice have significantly reduced numbers of long-lived plasma cells in the bone marrow, indicating the importance of BCMA for their survival (O'Connor et al., 2004).
In line with this finding, BCMA also supports growth and survival of multiple myeloma (MM) cells. Novak et al found that MM cell lines and freshly isolated MM cells express BCMA and TACI protein on their cell surfaces and have variable expression of BAFF-R protein on their cell surface (Novak et al., (2004) Blood 103(2):689-694).
Multiple myeloma (MM) is the second most common hematological malignancy and constitutes 2% of all cancer deaths. MM is a heterogenous disease and caused by mostly by chromosome translocations inter alia t(11; 14), t(4; 14), t(8; 14), del(13), del(17) (Drach et al., (1998) Blood 92(3):802-809; Gertz et al., (2005) Blood 106(8):2837-2840; Facon et al., (2001) Blood 97(6):1566-1571). MM-affected patients may experience a variety of disease-related symptoms due to, bone marrow infiltration, bone destruction, renal failure, immunodeficiency, and the psychosocial burden of a cancer diagnosis. As of 2006, the 5-year relative survival rate for MM was approximately 34% highlighting that MM is a difficult-to-treat disease where there are currently no curative options.
Exciting new therapies such as chemotherapy and stem cell transplantation approaches are becoming available and have improved survival rates but often bring unwanted side effects, and thus MM remains still incurable (Lee et al., (2004) J Natl Compr Canc Netw 8 (4): 379-383). To date, the two most frequently used treatment options for patients with multiple myeloma are combinations of steroids, thalidomide, lenalidomide, bortezomib or various cytotoxic agents, and for younger patients high dose chemotherapy concepts with autologous stem cell transplantation.
Most transplants are of the autologous type, i.e. using the patient's own cells. Such transplants, although not curative, have been shown to prolong life in selected patients. They can be performed as initial therapy in newly diagnosed patients or at the time of relapse. Sometimes, in selected patients, more than one transplant may be recommended to adequately control the disease.
Chemotherapeutic agents used for treating the disease are Cyclophosphamid, Doxorubicin, Vincristin and Melphalan, combination therapies with immunomodulating agents such as thalidomide (Thalomid®), lenalidomide (Revlimid®), bortezomib (Velcade®) and corticosteroids (e.g. Dexamethasone) have emerged as important options for the treatment of myeloma, both in newly diagnosed patients and in patients with advanced disease in whom chemotherapy or transplantation have failed.
The currently used therapies are usually not curative. Stem cell transplantation may not be an option for many patients because of advanced age, presence of other serious illness, or other physical limitations. Chemotherapy only partially controls multiple myeloma, it rarely leads to complete remission. Thus, there is an urgent need for new, innovative treatments.
Bellucci et al. (Blood, 2005; 105(10) identified BCMA-specific antibodies in multiple myeloma patients after they had received donor lymphocyte infusions (DLI). Serum of these patients was capable of mediating BCMA-specific cell lysis by ADCC and CDC and was solely detected in patients with anti-tumor responses (4/9), but not in non-responding patients (0/6). The authors speculate that induction of BCMA-specific antibodies contributes to elimination of myeloma cells and long-term remission of patients.
Ryan et al. (Mol. Cancer Ther. 2007; 6(11) reported the generation of an antagonistic BCMA-specific antibody that prevents NF-κB activation which is associated with a potent pro-survival signaling pathway in normal and malignant B-cells. In addition, the antibody conferred potent antibody-dependent cell-mediated cytotoxicity (ADCC) to multiple myeloma cell lines in vitro which was significantly enhanced by Fc-engineering.
Other approaches in fighting blood-borne tumors or autoimmune disorders focus on the interaction between BAFF and APRIL, i.e., ligands of the TNF ligand super family, and their receptors TACI, BAFF-R and BCMA which are activated by BAFF and/or APRIL. For example, by fusing the Fc-domain of human immunoglobulin to TACI, Zymogenetics, Inc. has generated Atacicept (TACI-Ig) to neutralize both these ligands and prevent receptor activation. Atacicept is currently in clinical trials for the treatment of Systemic Lupus Erythematosus (SLE, phase III), multiple sclerosis (MS, phase II) and rheumatoid arthritis (RA, phase II), as well as in phase I clinical trials for the treatment of the B-cell malignancies chronic lymphocytic leukaemia (CLL), non-Hodgkins lymphoma (NHL) and MM. In preclinical studies atacicept reduces growth and survival of primary MM cells and MM cell lines in vitro (Moreaux et al, Blood, 2004, 103) and in vivo (Yaccoby et al, Leukemia, 2008, 22, 406-13), demonstrating the relevance of TACI ligands for MM cells. Since most MM cells and derived cell lines express BCMA and TACI, both receptors might contribute to ligand-mediated growth and survival. These data suggest that antagonizing both BCMA and TACI might be beneficial in the treatment of plasma cell disorders. In addition, BCMA-specific antibodies that cross react with TACI have been described (WO 02/066516).
Human Genome Sciences and GlaxoSmithKline have developed an antibody targeting BAFF which is called Belimumab. Belimumab blocks the binding of soluble BAFF to its receptors BAFF-R, BCMA and TACI on B cells. Belimumab does not bind B cells directly, but by binding BAFF, belimumab inhibits the survival of B cells, including autoreactive B cells, and reduces the differentiation of B cells into immunoglobulin-producing plasma cells.
Nevertheless, despite the fact that BCMA; BAFF-R and TACI, i.e., B cell receptors belonging to the TNF receptor super family, and their ligands BAFF and APRIL are subject to therapies in fighting against cancer and/or autoimmune disorders, there is still a need for having available further options for the treatment of such medical conditions.
Accordingly, there is provided herewith means and methods for the solution of this problem in the form of a binding molecule which is at least bispecific with one binding domain to cytotoxic cells, i.e., cytotoxic T cells, and with a second binding domain to BCMA.
It must be noted that as used herein, the singular forms “a”, “an”, and “the”, include plural references unless the context clearly indicates otherwise. Thus, for example, reference to “a reagent” includes one or more of such different reagents and reference to “the method” includes reference to equivalent steps and methods known to those of ordinary skill in the art that could be modified or substituted for the methods described herein.
Unless otherwise indicated, the term “at least” preceding a series of elements is to be understood to refer to every element in the series. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the present invention.
The term “and/or” wherever used herein includes the meaning of “and”, “or” and “all or any other combination of the elements connected by said term”.
The term “about” or “approximately” as used herein means within ±20%, preferably within ±15%, more preferably within ±10%, and most preferably within ±5% of a given value or range. Throughout this specification and the claims which follow, unless the context requires otherwise, the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integer or step. When used herein the term “comprising” can be substituted with the term “containing” or “including” or sometimes when used herein with the term “having”.
When used herein “consisting of” excludes any element, step, or ingredient not specified in the claim element. When used herein, “consisting essentially of” does not exclude materials or steps that do not materially affect the basic and novel characteristics of the claim.
In each instance herein any of the terms “comprising”, “consisting essentially of” and “consisting of” may be replaced with either of the other two terms.